Patent GB-228742-A (GB)
Title: Improvements in or relating to automatic or semi-automatic telephone systems
IPC: H04Q3/42
Filed: 1924-04-02
Abstract: 228,742. Coventry Automatic Telephones, Ltd., and Wilman, C. W. Aprit 2, 1924. Automatic exchange systems.-In a registercontroller of the code-translating type in which the setting of the exchange registers causes a hunting switch to search for marked terminals, the position in which the hunting switch is brought to rest determining the translated digits to be sent out, the switch is brought to rest in a special position if it fails to find any marked terminals owing to the code combination dialled corresponding to no existing exchange. This is effected by arranging that the motion of the switch is always arrested when the special position is reached for the second time during a particular hunting operation. The register-controller is immediately released if a busy condition is reached at any stage of setting up a connection, and may also be released if the code digits indicate that the connection can be completed in the originating exchange by the numerical digits alone. The exchange digits are recorded on three step-by-step switches, the first two of which are serially related so that the first two digits apply ground to certain contacts in the bank of one wiper of the hunting switch, the, setting of the third digit register applying battery to contacts in the bank of a second wiper serially related to the first. The invention is described with reference to a system in which a calling subscriber is connected over a line-switch of the kind described in Specification 208,075 to a feed relay group, Fig. 2, similar to that described in Specification 223,385, leading to a first group selector, Fig. 3, and provided with a hunting switch 9 - - 12 of the " normal " type for connecting up an idle register-controller, Figs. 4 and 6 (which should be arranged with Fig. 6 to the right of Fig. 4, and Fig. 5 below Figs. 4 and 6). The system also includes means for metering calls, either once per call or according to the exchange required, in the latter case under the control of the register-controller; means for releasing the register-controller if the dialling of any digit is delayed; and means for calling a special operator by dialling the single digit 0. Seizure of idle register-controller. When the call has been extended to the relay group shown in Fig. 2, relays 1, 3 energize, the latter lighting a lamp 36 which indicates to an attendant if the subscriber delays the completion of the call, and a circuit is completed for relay 4 in series with stepping magnet 14, the mid-point of this circuit being connected to the test wiper 12 which in its normal position rests on a grounded terminal. Hunting thus takes place in the usual manner until an idle register-controller is found when relay 4 energizes, connects leads 43, 44 to wipers 11, 10, respectively, and completes a circuit from relay 7 over wiper 9 and relay 154 in series with a winding of dialling-tone transformer 360. The line relay 101 of the first selector, Fig. 3, energizes over lead 44 and wiper 10 and completes a circuit for relay 103, whilst relay 7 energizes and operates relays 8, 5. Relay 154 energizes to operate relay 159 which in turn energizes relays 157, 158 whereby ground is connected to leads 208, 209, the former ground connection operating relay 2 which locks up over off-normal contacts 15 of the switch 9 - - 12 to maintain the test lead 57 busy until the switch is completely restored, whilst the latter completes a holding circuit for relay 4. Registration of wanted number. The impulses for the several digits are repeated by relays 1, 154 over contacts 180, 169 and wiper 204 of a switch RS which is moved forward one step at the end of each digit. The first exchange digit is recorded on a register switch RR1 a wiper 330 of which has access over its first five terminals to a register switch RR2 and over its remaining terminals to a second similar switch (not shown). The terminals of a further wiper 329 of the switch RR1 are connected to wipers 319 of the two switches RR2 so that the second exchange digit is recorded on one or other of these latter switches and the combined effect of the first two digits is to connect ground over wipers 329, 319 to one of ninety conductors such as 376. The third exchange digit is recorded on a register switch RR3 and the four numerical digits on registers NR1 - - NR4. A Strowger switch may replace the registers RR1, RR2. Re-transmission of impulses; translation of exchange digits. When the switch RS moves into its fourth position after the exchange digits are completely recorded, it closes a circuit over wiper 203 for relay 156 which completes a circuit over contacts 174, 354, and wiper 328, for the stepping magnet 288 of a hunting switch MS. (There may be several switches MS, for example, four, but only the appropriate one hunts, this being determined by the setting of wiper 328). The started switch then hunts until its wiper 285 reaches a terminal connected to battery over lead 375, wiper 314, contact 176 and relay 351 at the same time that wiper 286 reaches a terminal grounded over lead 376 and wipers 319, 329. Relay 351 then energizes to stop the switch and connects up relay 350 so that at the first battery connection over interrupter 363, relay 350 energizes, and when battery is disconnected locks up over relay 348 which connects interrupter 363 to the impulse relay 155. At each succeeding connection of battery over the interrupter, relay 155 energizes to transmit an impulse to the line relay 101 of the first selector and also to complete a circuit for the magnet 344 of the counting switch CS. When wiper 342 reaches the contact marked by the setting of wiper 284 of switch MS, relay 349 energizes over the circuit 342, 284, 306, 331, 182 to stop the transmission of further impulses, to complete a circuit for magnet 310 of switch TS and to release relays 348, 350. The relapse of relay 350 closes a restoring circuit for switch CS, relay 349 remaining locked up over wiper 341 until the normal position is reached, when it releases to reconnect the interrupter, and at the same time switch TS moves to its 2nd position. Three more routing digits are then similarly transmitted under the control of wipers 283, 282, 281 after which switch TS moves to its 5th position and the numerical digits are re-transmitted in a similar manner but without translation. Less than four routing digits may be employed by jumpering terminals in the banks of wipers 281 - - 284 to the lead 380, in which case relay 349 energizes at once in the normal position of switch CS, and the switch TS is advanced a step. If any of the numerical digits has been completely re-transmitted before the next digit has been stored, relay 349 remains locked up over wipers 305, 205 to prevent the switch TS from advancing until the switch RS moves into its next position. Operation of first selector, Fig. 3. The first routing-digit is repeated at contact 108 to the vertical magnet 105, and at the end of the digit relay 103, which remained locked up during impulsing over contacts 104, 107, de-energizes and completes a circuit 113, 122, 123, 109, 116, 118 for rotary magnet 104 which is provided with interrupter springs of the type described in Specification 219,453. If the first trunk is busy, magnet 104 again operates over the test wiper 121 until an idle trunk is reached, when relay 102 operates to disconnect relay 101 and extend the connection. Further selectors may be of similar or known type. Release of register-controller. When switch TS reaches its 9th position, batery is removed from wiper 308, relays 159, 158, 157, 156 release, and restoring circuits are completed for switches RS, TS and registers RR1 - - RR3, NR1 - - NR4. The hunting switches MS have no normal position. The disconnection of ground from lead 209 releases relay 4 which at the back contacts of armatures 37, 38 completes the talking connection to the first selector. Release of register-controller if busy condition is reached during establishment of connection. In this case the selectors are of the type in which an intermittent battery connection is placed upon the upper talking conductor if a busy condition is reached, the said connection operating relay 152 over contacts 37, 48, 11, 172. Relay 152 opens the circuit of relay 159 and release follows as in the preceding paragraph. Delayed dialling. Relay 158 connects interrupter 191 to the lower winding of relay 151 which at the next battery connection operates armature 161 only and when battery is disconnected locks up over contact 168 and operates armature 162. If, when the interrupter again connects battery, no impulses have passed through relay 154 to unlock relay 151. the battery connection is extended over contact 162 to operate relav 152 and the register-controller is released as before. Releasing registercontroller after receipt of exchange code if no routing-digits are required, for example, for a call to the local exchange, the numerical equivalent of the exchange code being 196. In this case registers RR1 - - RR3 complete a circuit 329, 319, 335, 314, 176, 351 in which relay 335 operates to release relav 4, the numerical digits then going direct to the local switches. The opening of contact 39 releases relay 154 and the register-controller is restored as before. Calling special operator. The dialling of the single digit O causes wiper 329 of register RR1 to complete a circuit for relay 153 which energizes relay 156 to start the appropriate, hunting switch MS as before and to connect ground over leads 211, 373, to a particular terminal in the bank of wiper 286, the corresponding terminal of wiper 285 being connected to battery over lead 374 and wiper 314 in its normal position. The corresponding terminals of wipers 281 - - 284 are jumpered in the required manner for routing the call to an operator and the remaining operations proceed as before. Metering. The simultaneous operatio